PROVIDENCE, R.I.--(BUSINESS WIRE)--Jan. 19, 2005--Sention Inc. today announced that it has entered into an exclusive licensing and research collaboration agreement with Merck & Co., Inc. (NYSE: MRK) to develop a family of Merck compounds known as mGluR5 antagonists as potential treatments for Fragile X mental retardation. Fragile X is the most commonly inherited form of mental retardation.